WASHINGTON — U.S. Sens. Angus King and Carl Levin, who just returned from a fact-finding trip to Jordan and Turkey, called on the U.S. and other nations Tuesday to increase military pressure on President Bashar Assad’s regime in Syria.

Levin, D-Michigan, and Sen. Angus King, a Maine independent, spent five days in Jordan and Turkey talking to government officials as well as U.S. diplomatic and military personnel about the civil war raging in Syria.

The senators also visited camps in both nations where some of the hundreds of thousands of refugees from the war in Syria have fled.

“Assad’s brutality against the Syrian people has created a humanitarian crisis that threatens to destabilize the entire region,” the senators said Tuesday in a joint statement.

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Levin and King pointedly said they were not calling for American forces on the ground in Syria, but that the U.S. and other nations committed to stopping the violence there should train and equip opposition forces and consider other steps, including “options for limited, targeted strikes at airplanes, helicopters, missiles, tanks and artillery.”

Such military pressure could force a political settlement, they said.

“We, along with most Americans, are reluctant to see our military become involved in yet another war,” they said.

But, they added, “doing nothing may be the worst option of all,” potentially destabilizing U.S. allies, including Turkey and Jordan, and threatening Israel and other partners in the region.

They also called on U.S. allies to plan for “an inclusive political and military structure” to follow Assad, otherwise “a longer civil war could replace the current conflict,” resulting in much more brutality and potentially creating safe havens for terorrist groups.

Levin is chairman of the Senate Armed Services committee and an ex officio member of the Senate Intelligence Committee. King is a member of both committees.